Treatment for Vitamin B12 or Folate Deficiency Anemia
For vitamin B12 deficiency, administer hydroxocobalamin 1 mg intramuscularly three times a week for 2 weeks followed by maintenance treatment with 1 mg intramuscularly every 2-3 months for life; for folate deficiency, administer oral folic acid 5 mg daily for a minimum of 4 months, but always check and treat vitamin B12 deficiency before initiating folic acid treatment. 1, 2
Vitamin B12 Deficiency Treatment
Treatment Based on Clinical Presentation
- For vitamin B12 deficiency without neurological involvement: hydroxocobalamin 1 mg intramuscularly three times a week for 2 weeks, followed by maintenance treatment with 1 mg intramuscularly every 2-3 months for life 1, 2
- For vitamin B12 deficiency with neurological involvement: hydroxocobalamin 1 mg intramuscularly on alternate days until there is no further improvement, then transition to maintenance with hydroxocobalamin 1 mg intramuscularly every 2 months 1, 3
- Intramuscular administration is the preferred route for vitamin B12 replacement in cases of malabsorption 1
Treatment Based on Cause of Deficiency
- For patients with malabsorption causes (pernicious anemia, ileal resection, bariatric surgery), parenteral vitamin B12 will be required lifelong 1, 3
- Patients with more than 20 cm of distal ileum resected should receive prophylactic vitamin B12 injections (1000 μg) monthly for life 3
- For patients with normal intestinal absorption, initial treatment similar to that for patients with pernicious anemia may be indicated depending on the severity of the deficiency 4
Special Considerations
- High-dose oral vitamin B12 (1000 μg daily) may be effective in some patients, including those with pernicious anemia, but intramuscular therapy is preferred for severe deficiency or severe neurologic symptoms 5, 6
- Recent research shows that oral supplementation with 1000 μg/day of cyanocobalamin can improve vitamin B12 deficiency even in pernicious anemia, though this is not the traditional approach 6
Folate Deficiency Treatment
Important Warning
- Never administer folic acid before treating vitamin B12 deficiency, as it may mask underlying B12 deficiency and precipitate subacute combined degeneration of the spinal cord 1, 7
- Always check and treat for vitamin B12 deficiency before initiating folic acid treatment 1, 4
Treatment Protocol
- For folic acid deficiency, administer oral folic acid 5 mg daily for a minimum of 4 months 1
- Further investigations are recommended if there is suspicion of malabsorption 1
Diagnostic Considerations and Monitoring
Initial Assessment
- Use either total B12 or active B12 as the initial test for B12 deficiency 1
- Consider measuring methylmalonic acid as a confirmatory test when initial results are indeterminate 2
- Check both vitamin B12 and folate levels, as deficiencies may coexist 1
Monitoring Protocol
- During initial treatment of patients with pernicious anemia, serum potassium must be observed closely the first 48 hours and replaced if necessary 4
- Monitor hematocrit, reticulocyte count, vitamin B12, folate, and iron levels prior to and during treatment 4
- For patients with deficiency, monitoring should occur every 3 months until stabilization, then once a year 3
Common Pitfalls and Caveats
- Vitamin B12 deficiency that is allowed to progress for longer than 3 months may produce permanent degenerative lesions of the spinal cord 4
- Doses of folic acid greater than 0.1 mg per day may result in hematologic remission in patients with vitamin B12 deficiency but will not prevent neurologic manifestations 4
- Patients with pernicious anemia have about 3 times the incidence of carcinoma of the stomach as the general population, so appropriate tests for this condition should be carried out when indicated 4
- Certain medications like anticonvulsants, sulfasalazine, methotrexate, most antibiotics, and proton pump inhibitors may affect folate or B12 levels 1, 4, 5
- In patients with chronic inflammation, ferritin levels may be falsely elevated, masking iron deficiency that may coexist with B12 or folate deficiency 1